Excellent Adsorption Ability Research Articles

Adsorption of Orange G in Liquid Solution by the Amino Functionalized GO

Dye effluent damaged the water environment and human health with its massive discharge. In order to eliminate dye from the water environment, a variety of adsorbents were used to investigate dye removal. Graphene oxide (GO) attracted extensive attention due to its excellent surface property in the degradation of dye wastewater. Modified GO with multifunctional groups helped to improve adsorption performance. 3-Aminopropyltriethoxysilane modified GO (AS-GO) was fabricated for the removal of Orange G (OG) in this study. The results showed that AS-GO had an excellent adsorption ability of OG. During the reaction process, the maximum adsorptive capacity of OG was up to 576.6 mg/g at T = 313 K and pH = 3 with the initial OG concentration of 100 mg/L and the initial adsorbent dose of 2.5 g/L. The adsorption kinetic process of AS-GO conformed to the pseudo-second-order and Langmuir models. The spontaneous and endothermic adsorption of OG occurred in the adsorption process. The main adsorption mechanisms were electrostatic, π–π and hydrogen bonding interactions in the reaction process. After four cycles of AS-GO, it maintained high removal efficiency owing to its remarkable stability. The scheme of GO modified with AS could hinder the agglomeration of GO and provide more active sites, which would further enhance the adsorption properties and expand its application in water purification.

Partially reduced CeO2/C@CNT with high oxygen vacancy boosting phosphate adsorption as CDI anode

Phosphorus in water is the main inducement for eutrophication and deterioration of water quality. Cerium oxide has excellent adsorption ability for phosphate, but its activity and conductivity need to be improved for capacitive deionization (CDI) application. Herein, a carbon nanotube (CNT)-twined CeO2/C composite was synthesized by in-situ growth of Ce-BTC in CNT matrix followed by carbonization. The ultrafine CeO2 particles were uniformly dispersed in carbon matrix, improving the electrical conductivity and effective active sites. Via hydrazine reduction, the content of Ce(III) and oxygen vacancy of the obtained CeO2/C-R@CNT were enhanced, boosting the activity of electrode for phosphate adsorption. As an anode, CeO2/C-R@CNT delivered the maximum phosphate removal capacity of 109.5 mg P/g. The adsorption performance was investigated by analyzing adsorption kinetics and adsorption isotherms. The corresponding adsorption mechanism was studied by pH analysis, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The electrode showed high selectivity to phosphate adsorption, and the separation factor arrived at 8.7 in the mixture solution with the Cl–/P concentration ratio of 15. In addition, CeO2/C-R@CNT retains the P adsorption capacity of 95 % in 30 cycles. The phosphate in actual water was totally removed with good repeatability, proving the high practicability for water treatment.

Adsorption and Removal of Phosphate from Wastewater Using Lignin-Based Adsorbent Modified with Lanthanide: Characterization, Performance, and Mechanisms

Water eutrophication due to the discharge of wastewater containing phosphate has aroused considerable concern around the world, and adsorption has been identified as one of the viable solutions to solve the problem. It is crucial to develop an eco-friendly and cost-effective adsorbent for preventing eutrophication of water bodies. In this study, we developed a simple coprecipitation approach to prepare a lanthanum-based modified calcium lignosulfonate (La-CL) for treating phosphate wastewater. La-CL exhibited excellent adsorption ability for phosphate due to its high loading of lanthanum (59.29%) and large specific surface area (175.3 m2 g–1). In a wide range of pH values (2–11), the adsorption capacity of phosphate onto La-CL remained stable, and the removal rate was above 90%. The maximum adsorption capacity could reach 107 mg g–1 for phosphate at optimum pH = 7, and the adsorption reached equilibrium within 240 min. After seven consecutive regeneration adsorption experiments, La-CL could still maintain a desorption rate of more than 75%, indicating that La-CL exhibited a certain degree of regenerative performance. Moreover, the adsorption behaviors of phosphate onto the La-CL adsorbents were fitted to the Freundlich isotherm and pseudo-second-order model, suggesting chemical adsorption and a heterogeneous adsorption process. The mechanistic studies revealed that ligand exchange played a significant role in the adsorption of phosphate. This study would provide a strategy of “treating waste with waste” for removing phosphate from wastewater at low concentrations based on La-CL.

Polydopamine-assisted polyethyleneimine grafting on electrospun cellulose acetate/TiO2 fibers towards highly efficient removal of Cr(VI)

Highly efficiently removing hazardous heavy metal ions from water is very important from a viewpoint of maintaining the sustainable development of ecological environment. In this work, a novel adsorbent based on the cellulose acetate (CA) was developed, which was fabricated through the blend electrospinning of CA and titanium dioxide (TiO2) nanoparticles, surface modification by polydopamine (PDA) and then grafted by polyethyleneimine (PEI). The composite CA/TiO2 electrospun fibers exhibit the porous structure, while the surface modification by PDA-assisted PEI grafting has no apparent effect on morphology of the electrospun fibers. The CA/TiO2@PDA@PEI composite fibers show the large number of amine groups, and the surface of the fibers can be positively charged in the acidic solution. Adsorption measurements show that the fibrous membrane samples exhibit excellent adsorption ability toward Cr(VI), and the maximum adsorption capacity is as high as 357.1 mg g−1 at solution pH value of 2, solution temperature of 25 °C. Specifically, about 72.1 % Cr(VI) can be directly reduced to harmless Cr(III) during the adsorption measurement, which is much higher than those of the almost adsorbents reported in literatures. The excellent adsorption/reduction ability endows the fibrous membranes with great potential application in removing highly hazardous Cr(VI) from wastewater.

Design of hyper-cross-linked polymers with tunable polarity for effective preconcentration of aflatoxins in grain

Aflatoxins (AFs) as a category of polar mycotoxins possess a significant threat to human health. However, constructing of sorbents with suitable polarity for the preconcentration of AFs remains poorly developed due to the difficulty in tuning the polarity of the sorbents optionally. Herein, a series of novel hypercrosslinked polymers (OP-HCPs) with adjustable polarity were designed and synthesized by varying selection of alkylphenol ethoxylates monomers and benzyl halides crosslinkers for the preconcentration of AFs. By integration of magnetism into OP-HCP, a novel magnetic sorbent (M-OP10-DCX) was prepared to readily pre-concentrate of AFs from rice and maize samples prior to high performance liquid chromatography-fluorescence detection (HPLC-FD). Benefiting from the unique polarity interaction between M-OP10-DCX and AFs, the M-OP10-DCX displayed excellent adsorption ability for the AFs. Good linearity in the range of 5.0–4000 pg g−1 (R2 > 0.9983), low limits of detection (signal-to-noise ratio of 3) of 1.5–50 pg g−1 and high enrichment factors of 105–205 were achieved. The recoveries of the method ranged from 82.8 % to 115 % with the relative standard deviation less than 8.0 %. This work provided a new strategy for the rational design of HCPs with tunable polarity as valuable tools for specific adsorption of different kinds of compounds.

Fluorescent porous organic polymers for detection and adsorption of nitroaromatic compounds

A fluorescent porous organic polymer (FPOP) with strong fluorescence and tunable emission colors, was synthesized through a simple cost-effective method via Scholl coupling reaction. Experiments proved the stability and excellent detection and adsorption ability, and microporous nature of the material. Luminescence of FPOP was quenched when addition of nitroaromatic compounds. The properties along with large-scale and low-cost preparation make these FPOP potential candidates for fluorescence detection of nitroaromatic compounds. Additionally, FPOP shows higher adsorption capacity and rate than other reported adsorbents, and has the possibility of being an effective adsorbent for industrial usage. Moreover, a fluorescent test paper was further developed and is found to be sensitive to 10–8 M level, complete with a rapid response time and visual detection. This newly developed strategy may open up an avenue for exploring porous polymers, particularly those with a strong fluorescence, for the large-scale fabrication of FPOP for various advanced applications.

Recyclable 3D konjac glucomannan/graphene oxide aerogel loaded with ZIF-67 for comprehensive adsorption of methylene blue and methyl orange

To solve the problem that it is difficult to recycle the ZIF-67 in aqueous solution, a porous self-supporting material (KGM/GO) was prepared by using biomass KGM. And then ZIF-67 crystal was loaded onto KGM/GO solid substrate by in-situ growth method so that a novel KGM/GO/ZIF-67 composite aerogel was obtained. FT-IR and SEM characterization showed that ZIF-67 was successfully loaded on KGM/GO substrate by covalent bonding, and the adsorption site of composite aerogel surface was uniform. The N2 adsorption/desorption testing results showed that the porosity of composite aerogel changed from 86.48 % to 91.18 % after loading ZIF-67. It provides enough diffusion channel and active adsorption sites. Moreover, the as-prepared composite aerogel showed excellent adsorption ability to both methylene blue and methyl orange, and the maximum adsorption capacities were as high as 185.67 mg/g (pH = 8) and 130.2 mg/g (pH = 2), respectively. Noted that after five cycles, the adsorption capacity to methylene blue and methyl orange were still up to 174.4 mg/g and 118.3 mg/g, which exhibited high adsorption capacity and excellent reusability. Therefore, loading ZIF-67 on KGM/GO substrate can enhance the adsorption and recovery performance of ZIF-67. The method provides a new possibility for the treatment of complex dye-containing wastewater.

Theoretical design and preparation of ionic liquid-based magnetic nanoparticles for the magnetic dispersive solid-phase extraction of benzimidazoles in human plasma

Conductor-like screening model for realistic solvents (COSMO-RS) theoretical chemical model is an effective tool for predicting the thermodynamic properties of solvents. In this study, 144 ionic liquids (ILs) were designed and screened by COSMO-RS with affinity interactions with benzimidazoles (BZDs) as the target. Ionic liquid-based magnetic nanoparticles (IL-MNPs, Fe3O4@SiO2@MAPs@PIL-POSS) were prepared by the selected diene ILs (1-allyl-3-vinylimidazolium chloride [Avim]Cl) and polyhedral oligomeric silsesquioxane (POSS) coating Fe3O4 by free radical polymerization. As the adsorbent, the Fe3O4@SiO2@MAPs@PIL-POSS has great magnetic recovery ability and excellent specific adsorption ability for BZDs. The magnetic dispersive solid-phase extraction (MDSPE) of BZDs was established by optimizing the adsorption and desorption parameters. It is worth noting that the sample pretreatment only took 5 min. Combined with HPLC-MS/MS, a trace detection method for 7 trace BZDs in human plasma was established. In the method validation, the recoveries ranged from 79 % to 99 %, with relative standard deviations (RSDs) of 1.8 % to 8.8 %. The linear range were 1–1,000 μg/L. As a representative BZD, the adsorption kinetics and thermodynamic behavior of carbendazim on Fe3O4@SiO2@MAPs@PIL-POSS were analyzed to verify the adsorption mechanism, which is consistent with the results of IL screened by COSMO-RS. Therefore, it is feasible to theoretically screen IL and design IL-MNPs as specific adsorption materials. Furthermore, the theoretical design of MDSPE methods for target molecules has potential.

Hexagonal boron nitride nanosheets based magnetic solid phase extraction for the extraction of phenoxy carboxylic acid herbicides from water samples followed by high-performance liquid chromatography-tandem mass spectrometry

High-efficiency caption of pesticide residue is of vital significance for environmental safety monitoring. Herein, a hexagonal boron nitride nanosheets-based magnetic composite (Fe3O4@h-BNNSs) was synthesized and applied for the magnetic solid phase extraction (MSPE) of five phenoxy carboxylic acid (PCA) herbicides from water samples. Based on the π-π interaction, hydrogen bond and halogen bond, the Fe3O4@h-BNNSs composite showed excellent adsorption ability towards PCA herbicides. Several main variables that influenced the extraction efficiencies of PCA herbicides were investigated and optimized via single-factor experiment. Combining this Fe3O4@h-BNNSs composite-based MSPE with high-performance liquid chromatography-tandem mass spectrometry, a novel sensitive method for the analysis of PCA herbicides was developed. Under the most favorable conditions, the proposed method displayed good linear ranges (20.0-10000.0 ng L−1), low limits of detection (5.6-10.3 ng L−1), satisfactory precisions (1.1-6.8%) and recoveries (76.6-107.2%). Overall, the present work can be a versatile and worthy utility for the determination of PCA herbicides from different water samples.

One-step preparation of macroporous zein microspheres by solvent diffusion for dye adsorption

Macroporous microspheres have attracted significant interest in various fields since macropores endow with fast mass transfer. However, constructing the macropore mostly requires additional porogenic agents and complex steps. Here, a simple solvent diffusion strategy has been developed for the rapid preparation of macroporous protein microspheres. Based on the strategy, the macropores in the microspheres are created by the removal of the trapped aqueous phase. The results show that the average particle size of the prepared microspheres is centered at about 10 µm. The pore size of the microspheres ranges from 50 nm to about 1 µm and can be controlled by adjusting the parameters of surfactant, temperature, and concentration during the preparation process for different requirements. Finally, the macropore microspheres are characterized by the adsorption of Congo red dyes, which show excellent adsorption ability. According to these results, these macroporous protein microspheres have a practical potential for applications in adsorption and biomedicine fields.

Preparation of VCo-MOF@MXene composite catalyst and study on its removal of ciprofloxacin by catalytically activating peroxymonosulfate: Construction of ternary system and superoxide radical pathway

The synergistic effect between transition metal active centers and the generation of multiple removal pathways has a significant impact on the catalytic activation efficiency of peroxymonosulfate. In this work, a kind of composite catalyst was prepared by growing VCo-metal–organic frameworks (VCo-MOF) in-situ on the surface of Ti3C2Tx by a solvothermal method. The morphology and structure are characterized by Transmission Electron Microscope (TEM), Energy Dispersion Spectrum (EDS), Atomic Force Microscope (AFM), etc. Response surface methodology was used to optimize the experimental conditions. Only 5 mg catalyst can be used to effectively activate PMS and remove 96.14 % ciprofloxacin (CIP, 20 mg/L) within 30 min. The removal effect of catalyst on CIP in different actual water environment was explored. In addition, the fluorescence spectrum test also verified the effective removal of ciprofloxacin. V-Co-Ti ternary system provides a wealth of active sites for CIP removal. Cyclic voltammetry (CV) and lear sweep voltammetry (LSV) tests showed the existence of the electron transfer pathway. The results of density functional theory (DFT) calculation show that VCo-MOF@Ti3C2Tx has excellent adsorption and activation ability for PMS. At the same time, the hydrophilicity of the catalyst makes PMS more inclined to react with water molecules, which promotes the formation of a unique superoxide radical path.

CuBi2O4/calcined ZnAlBi-LDHs heterojunction: Simultaneous removal of Cr(VI) and tetracycline through effective adsorption and photocatalytic redox

In order to solve the pollution of heavy metals and organic antibiotic in the water environment, a novel CuBi2O4/calcined ZnAlBi layered double hydroxides (CBO/CLDHs) composite was constructed and prepared via an ultrasonic-assisted calcination method for the adsorption and photocatalysis synergetic effect. Through varying the composition ratio, pH value, initial pollutant concentration and other pollutant interference, the simultaneous removal ability including adsorption and photocatalysis of as-prepared CBO/CLDHs composites for Cr(VI) and tetracycline pollutants was discussed. In particular, the CBO/CLDHs-1/15 composite showed that the removal efficiencies of Cr(VI) (40 mg/L) and tetracycline (40 mg/L) were both above 95%. Meanwhile, the XPS results confirmed that the toxic Cr(VI) was gradually reduced to non-toxic Cr(III) under visible light irradiation. The enhanced adsorption and photocatalytic activity was mainly attributed to the uniform distribution of calcined ZnAlBi layered double hydroxides nanosheets on the CuBi2O4 microrods and the formation of heterojunctions. Moreover, cycle performance results revealed that the CBO/CLDHs-1/15 composite maintained high removal activity and stable structure after 4 photocatalytic cycles, and even showed a good adaptability while applied to the actual water in production and living environments. These results exhibited that the as-prepared CBO/CLDHs-1/15 composite has excellent adsorption and photocatalytic ability for the simultaneous removal of Cr(VI) and tetracycline, with a great potential application in practical waste water treatment field.

Facile fabrication of spherical flower-like Mg(OH)2 and its fast and efficient removal for heavy metal ions

Spherical flower-like Mg(OH)2 was fabricated from MgSO4 effluent and its adsorption performance for heavy metal ions was evaluated. The appropriate fabrication conditions are as follows: Mg2+/NH4OH molar ratio of 1:0.5, temperature of 120 °C and time of 1 h at Mg2+ concentration of 2 mol/L. Spherical flower-like Mg(OH)2 composed of ultra-thin sheets exhibits an excellent adsorption ability for Ni2+, Cu2+, Zn2+, Pb2+, Fe3+ and Co2+, and the adsorption reaches the equilibrium in 6 min. The maximum adsorption capacities of the studied heavy metal ions onto Mg(OH)2 at 20 °C are 58.55, 85.84, 44.94, 485.44, 625.00 and 27.86 mg/g, respectively. The adsorption is well fitted by the Langmuir model, indicating that the adsorption is monolayer. The adsorption kinetics follows the pseudo-second- order model. Chemisorption is the operative mechanism. Spherical flower-like Mg(OH)2 is a qualified candidate for heavy metal ions removal.

Hierarchical Nanoflowers of MgFe2O4, Bentonite and B-,P- Co-Doped Graphene Oxide as Adsorbent and Photocatalyst: Optimization of Parameters by Box-Behnken Methodology.

In the present study, nanocomposites having hierarchical nanoflowers (HNFs) -like morphology were synthesized by ultra-sonication approach. HNFs were ternary composite of MgFe2O4 and bentonite with boron-, phosphorous- co-doped graphene oxide (BPGO). The HNFs were fully characterized using different analytical tools viz. X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersion spectroscopy, transmission electron microscopy, X-ray diffraction, vibrating sample magnetometry and Mössbauer analysis. Transmission electron micrographs showed that chiffon-like BPGO nanosheets were wrapped on the MgFe2O4-bentonite surface, resulting in a porous flower-like morphology. The red-shift in XPS binding energies of HNFs as compared to MgFe2O4-bentoniteand BPGO revealed the presence of strong interactions between the two materials. Box–Behnken statistical methodology was employed to optimize adsorptive and photocatalytic parameters using Pb(II) and malathion as model pollutants, respectively. HNFs exhibited excellent adsorption ability for Pb(II) ions, with the Langmuir adsorption capacity of 654 mg g−1 at optimized pH 6.0 and 96% photocatalytic degradation of malathion at pH 9.0 as compared to MgFe2O4-bentonite and BPGO. Results obtained in this study clearly indicate that HNFs are promising nanocomposite for the removal of inorganic and organic contaminants from the aqueous solutions.

Effect of Hydroxyapatite on the Migration of Fe(III) Ions: Kinetic, Equilibrium and Thermodynamic Study.

The recycling and regeneration of Fe(III) is the key point for promoting the oxidation reaction of ore to produce acidic mine drainage (AMD). Hydroxyapatite (HAP) has excellent adsorption ability of Fe(III), which has good biocompatibility and is widely distributed in nature. In order to achieve the source treatment of AMD, the migration and transformation of Fe(III) in the presence of HAP were systematically investigated. In this study, the influence of HAP on the migration of Fe(III) was evaluated though the transformation capacity of Fe(III) by HAP. The adsorption transformation kinetic, equilibrium and thermodynamics of Fe(III) using HAP were also systematic investigated. The transformation efficiency of Fe(III) increased with the increasing initial pH value and reached 99.8% at a pH of 5 due to the hydrolysis reaction. The transformation efficiency was also up to 99% at an initial pH of 2 when the reaction temperature increased to 313 K. However, the transformation capability of Fe(III) decreases with reaction temperature. The kinetics of the adsorption of Fe(III) fitted the pseudo second order kinetic model. Experimental results were also analyzed by the Langmuir isotherm equations at room temperatures. RL separation factor for Langmuir isotherm showed that the migration of Fe(III) is successfully hindered by HAP. Various thermodynamic parameters such as enthalpy (ΔH), Gibbs free energy (ΔG) and entropy (ΔS) changes were computed, which showed that the transport lag of Fe(III) caused by HAP is spontaneous and endothermic.

One-Step Catalytic Activation Promoting Pore Development of Zhundong Coal-Based Activated Coke: A Compared Study with Conventional Carbonization–Activation Combined Process

Hierarchically porous activated coke is widely applied in pollutant removal due to its excellent molecule adsorption and transportation ability. Catalytic activation with the participation of alkali/alkaline earth metal salt has been reported to be effective for constructing hierarchical pore configuration; however, the technical condition remains to be explored for providing guidance to practical preparation process. Herein, the relationship between the porous structure of Zhundong coal-based activated coke and the technical condition during catalytic activation is systematically discussed. Based on comparisons of porous structures obtained under different carbonization–activation conditions, one-step catalytic activation is demonstrated to be more favorable for pore development than traditional carbonization–activation process. Physicochemical structural analyses of the precursor and the prepared activated coke reveal that pore development during catalytic activation is also related to the surface chemistry of the precursor and particle size. Amplified preparation experiments in rotary kiln further verify the potential of one-step catalytic activation in industrial production. As a proof of application, selective catalytic reduction tests show that the prepared hierarchically porous activated coke via one-step catalytic activation exhibits high efficiency in NO removal. This work highlights the promoting role of one-step catalytic activation in pore development, providing guidance for preparing high-performance activated coke under practical industrial conditions.

ZIF-8 Modified Nanofiber Composite Window Screen for Efficient Indoor PM2.5 and Formaldehyde Removal

Because people spend a lot of time indoors every day, the presence of particulate matter with a diameter less than 2.5 µm (PM2.5) and volatile organic molecular substances in indoor air adversely affect public health. These toxic compounds can be removed from the air using high-efficiency air-filter materials with adsorption capacity. Metal-organic frameworks (MOFs) are among the most suitable materials for air purification as they are synthetic porous materials with excellent adsorption ability. In this study, the zeolitic imidazolate framework-8 (ZIF-8) is uniformly grown on the surface of polyacrylonitrile (PAN) nanofibers using an in situ growth method to prepare ZIF-8@PAN nanofiber composite membranes. The nanofiber composite membrane effectively removes PM2.5 and formaldehyde from the air. After loading the optimal amount of ZIF-8, the filtration efficiency of the nanofiber membrane for salt aerosol with a diameter of 0.3 µm increases from 90.3 % to 96.9 %, and the removal rate of formaldehyde becomes 98 % within 20 min in the enclosed space of the laboratory. Moreover, after five repeated tests, the formaldehyde adsorption rate remains above 80 %. In addition, ZIF-8@PAN nanofiber membranes are used to fabricate anti-haze window screens, which have great potential to improve indoor air quality and mitigate related health risks.

Fe/Acid‐montmorillonite as effective Fenton‐like catalyst for the removal of methylene blue

AbstractBackgroundMost dyes are toxic, carcinogenic, and mutagenic, all of which cause severe harm to human health and the environment. Therefore, it is essential to find the most suitable method to treat dye wastewaters before discharge. In this study, the natural Ca‐type montmorillonite (Ca‐MMT) was activated by HNO3 (20 wt.%) solution under different temperatures to obtain acid‐activated MMT (Acid‐MMT). Fe (10 wt.%) was supported on Acid‐MMT (Fe/Acid‐MMT) via the impregnation method using Fe(NO3)3·9H2O as a precursor. Meanwhile, the removal of methylene blue (MB) by heterogeneous Fenton‐like reaction using Fe/Acid‐MMT as catalyst was evaluated. The material was characterized by Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), X‐ray photoeletron spectroscopy (XPS), scanning electron microscopy (SEM), N2 adsorption–desorption at low temperature, and the temperature program desorption of NH3 (NH3‐TPD) techniques.ResultsThe acidity and textural properties of the Acid‐MMT were adjusted by varying the acid activation temperature. Moreover, the amount of acidity and the surface area of the catalyst had a noticeable effect on the removal efficiency of MB. Fe‐supported Acid‐MMT activated by HNO3 at 100°C (Fe/Acid‐MMT‐100) catalyst exhibited the highest removal efficiency of MB. The removal efficiency of the MB was more than 97.8% under the following reaction conditions: H2O2 concentration of 0.85 mmol·L−1, Fe/Acid‐MMT‐100 dosage of 0.75 g°L−1, temperature of 50°C, and initial solution pH of 3.0–9.0.ConclusionAn efficient Fe/Acid‐MMT catalyst for a Fenton‐like reaction was obtained by optimizing the acid treatment temperature of Ca‐MMT. The synergistic effect between its excellent adsorption ability and the ∙OH generated from H2O2 activated by Fe/Acid‐MMT would enhance MB removal efficiency in a Fenton‐like system. © 2022 Society of Chemical Industry (SCI).

Migration study of phenolic endocrine disruptors from pacifiers to saliva simulant by solid phase microextraction with amino-functionalized microporous organic network coated fiber

Parabens, bisphenols, and triclosan are used in many baby products, including pacifiers. However, the migration through oral saliva will result in a potential health risk. The present study proposes a sensitive and simple method for the analysis of these chemicals in saliva simulants by solid phase microextraction (SPME) with amino-functionalized microporous organic network (MON-NH2) coated fiber. The MON-NH2 showed an excellent adsorption ability for phenolic compounds. The adsorption isotherm fitted the Langmuir isotherm model and the adsorption kinetics followed the pseudo second-order model. The developed SPME method exhibited wide linear ranges (0.005–500 µg/L), good linearity, low limits of quantitation (0.005 µg/L), great recoveries (87.0–112.5 %), and excellent precision (RSD < 8.3 % for intra-day and RSD < 13.7 % for inter-day). Mathematical models based on Fick’s second law were applied to predict migration from pacifiers into saliva simulants and a good fit between theoretical and experimental migration results was found. The daily exposure assessment results indicated that these chemicals in pacifiers do not pose unacceptable health risks to infants. However, exposure risks still should be monitored and appropriate precautions are still needed to protect infants from exposure to these chemicals.

Portable and on-site electrochemical sensor based on surface molecularly imprinted magnetic covalent organic framework for the rapid detection of tetracycline in food

In this study, for the first time, surface molecularly imprinted magnetic covalent organic frameworks (Fe3O4@COFs@MIPs) were combined with disposable screen-printed electrode (SPE) to construct a portable and on-site electrochemical sensor for the rapid detection of tetracycline (TC). The Fe3O4@COFs@MIPs, which was prepared by layer-by-layer modification method, had good magnetism and excellent adsorption ability. With the help of disposable SPE, equipped with a magnet, the electrode modification process was simplified and the detection efficiency was improved. Under optimal conditions, the fabricated electrochemical sensor exhibited linearity ranging from 1 × 10−10 to 1 × 10−4 g mL−1. It had good selectivity, excellent reproducibility, desirable stability and remarkable applicability. The fabricated sensor was successfully applied to detect TC in real samples with satisfactory recoveries (96.15–106.20%). The detection strategy separated the recognition and adsorption process from the electrochemical detection process, providing a design idea for the application of COFs in the construction of high-efficiency molecularly imprinted electrochemical sensors.